Characterizing Country Settings: Development of a Base Document in the Backdrop of

Climate Change Impacts

June 2009

Climate Change Cell Department of Environment

Characterizing Country Settings: Development of a Base Document in the Backdrop of Climate Change Impacts

Characterizing Country Settings: Development of a Base Document in the Backdrop of Climate Change Impacts Published by Climate Change Cell Department of Environment, Ministry of Environment and Forests Component 4b Comprehensive Disaster Management Programme, Ministry of Food and Disaster Management Bangladesh Date of Publication June 2009 The study has been conducted by Bureau of Research, Testing and Consultation of Bangladesh University of Engineering & Technology, commissioned by the Climate Change Cell.

Members of the study team are: Dr. Mashfiqus Salehin, Principal Investigator and Dr. Mohammad Asad Hussain (IWFM-BUET) Citation CCC, 2009. Characterizing Country Settings: Development of a Base Document in the Backdrop of Climate Change Impacts. Climate Change Cell, DoE, MoEF; Component 4b, CDMP, MoFDM. June 2009, Dhaka. Contact Climate Change Cell Room 514, Paribesh Bhabhan E-16, Sher-E-Bangla Nagar, Agargaon, Dhaka-1207, Bangladesh Phone: (880-2) 9111379 Extension 147; 0666 2301 021 E-mail: info@climatechangecell-bd.com Website: http://www.climatechangecell-bd.org ISBN: 984 -300 - 003323 - 1

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Acknowledgement

Climate Change Cell of the Department of Environment expresses gratitude to the collective wisdom of all stakeholders including experts, professionals and practitioners dedicated to the service of climate change risk management particularly in climate change adaptation and modeling.

Mention of the research team, Bureau of Research, Testing and Consultation (BRTC) and Institute of Water and Flood Management (IWFM) of Bangladesh University of Engineering & Technology (BUET) is obvious.

Cell also likes to mention Ian Rector, CTA, CDMP, Khondaker Rashedul Haque, PhD, former DG, DoE, Mohammad Reazuddin, former Director, DoE and Component Manager of the Cell, and Ralf Ernst, former Technical Adviser, Climate Change Cell for their support and inspiration provided during initial stages of the research programme.

Acknowledgement is due to Technical Advisory Group (TAG) of the Cell for their valuable contribution in identification of concepts, evaluation of concept proposals, development of methodology and finalizing the research reports.

Views of government officials, civil society members and development partners in several stakeholders consultation workshops enriched the research outcome.

Special gratitude to the distinguished experts, Dr. M. Asaduzzaman, Research Director, Bangladesh Institute of Development Studies (BIDS) and Professor Dr. Rezaur Rahman, IWFM-BUET, who as peer-reviewers, provided valuable insight on research methodology, analysis and findings.

Cell is grateful to the Department of Environment, Ministry of Environment and Forests for the initiative for publication of the research paper. In this respect, Md. Nojibur Rahman, former Director General, DoE supported the Cell throughout the initiative and provided much needed directives for the publication.

Contribution of Dr. Fazle Rabbi Sadeque Ahmed, Director, DoE in finalizing the research document is invaluable.

Mirza Shawkat Ali and Md. Ziaul Haque, Deputy Director, DoE extended their allout support during whole period of the research programme.

Acknowledgement is due to the Department for International Development (DFID) and United Nations Development Programme (UNDP) for their continued support to the Climate Change Cell in its effort to facilitate the climate change research programme.

Finally, Cell gratefully acknowledges the contribution of Abu M. Kamal Uddin, Programme Manager and Mohammad Showkat Osman, Research Officer, Climate Change Cell who were involved in the over all management of the research program; Md. Nasimul Haque, Information and Communication Expert who provided valuable insight in development of the research program and Md. Mezbanur Rahman, Research Officer who provided valuable assistance in preparing the report for publication.

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Foreword

The impacts of global warming and climate change are worldwide. For Bangladesh they are most critical because of its geographical location, high population density, high levels of poverty, and the reliance of many livelihoods on climate-sensitive sectors, such as agriculture, fisheries.

To address current impacts and manage future risks of climate change and variability towards development of a climate resilient Bangladesh, the government has established the Climate Change Cell (CCC) in the Department of Environment (DoE) under the Comprehensive Disaster Management Programme (CDMP). Climate change research, covering modeling and adaptation is one of the major activities of the Cell.

CCC in association with its Technical Advisory Group (TAG) and other stakeholders identified a set of research activities related to climate change in Bangladesh through a number of consultations. The activities have been prioritized and a number of projects have been commissioned in last few years.

Bangladesh is recognized worldwide as one of the countries most vulnerable to the impacts of climate change because of its geographical location and physiographic features, and low capacity to adapt to change. The country is prone to a multitude of natural hazards (e.g. floods, droughts, storm surge, salt water intrusion, river erosion, etc.) and vulnerable to the adverse impacts of future climate change. Before addressing climate change adaptation in the context of development, it is important to recognize that todays climate has already influenced economic opportunities and development prospects, and the projected climate change impacts would in fact reinforce many of these baseline stresses. It is important to characterize existing vulnerabilities; the first task of defining the present risk environment is to characterize the natural, physical, socio-economic and institutional settings of the country.

This study is an attempt to develop a base document describing the country settings including natural settings, physical infrastructures and socio-economic conditions in the backdrop of climate change. The report provides brief description of institutional settings, classification of major livelihood groups and their vulnerabilities to climatic hazards.

Even though, the study is not a comprehensive one, it is expected that this will create opportunity for the researchers, practitioners and other stakeholders to share the findings and plan a more comprehensive study. Such initiatives will provide policy makers and planners with useful information to formulate viable adaptation policies, strategies and action plan to combat climate change.

Zafar Ahmed Khan, PhD Director General

Department of Environment

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Acronyms and Abbreviations

AEZ Agro Ecological Zone

BADC Bangladesh Agricultural Development Corporation

BARC Bangladesh Agricultural Research Council

BARI Bangladesh Agricultural Research Institute

BBS Bangladesh Bureau of Statistics

BIWTA Bangladesh Inland Water Transport Authority

BRAC Bangladesh Rural Advancement Committee

BWDB Bangladesh Water Development Board

CBOs Community Based Organizations

CEGIS Centre for Environmental and Geographic Information System

CEP Coastal Embankment Project

CRED Centre for Research on the Epidemiology of Disasters

CRRAP Community Risk Reduction Action Plan

DAE Department of Agricultural Extension

DDCC District Development Coordination Committee

DMB Disaster Management Bureau

DoE Department of Environment

DoF Department of Fisheries

DPHE Department of Public Health Engineering

DTW Deep Tube well

ECNEC Executive Committee of National Economic Council

ECNWRC Executive Committee of National Water Resources Council

EEZ Exclusive Economic Zone

EPZ Export Processing Zone

FAO Food and Agricultural Organization of the United Nations

FC Flood Control

FCD Flood Control and Drainage

FCDI Flood Control, Drainage and Irrigation

GBM Ganges Brahmaputra Basin

GDP Gross Domestic Products

GIS Geographic Information System

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HYV High Yielding Variety

IPCC Inter-governmental Panel on Climate Change

ISPAN Irrigation Support Project for Asia and the Near East

IWT Inland Water Transport

LCA Livelihood Capital Assets

LDC Least Developed Country

LGED Local Government Engineering Department

LGI Local Government Institutions

LLP Low Lift Pump

MSL Mean Sea Level

NGOs Non Government Organizations

NWMP National Water Management Plan

NWRC National Water Resources Council

OECD Organization for Economic Co-operation and Development

ICZMP Integrated Coastal Zone Management Plan

RVCC Reducing Vulnerability to Climate Change

SBCP Sundarban Bio-diversity Conservation Project

STW Shallow Tube well

UDCC Upazila Development Coordination Committee

UNESCO United Nation Education Science and Cultural Organization

UNFCC United Nations Framework Convention on Climate Change

UNICEF United Nations Children's Fund

WARPO Water Resources Planning Organization

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Table of Contents

Acronyms and Abbreviations vTable of Contents viiList of Tables ixList of Figures xExecutive summary xiii Chapter 1 Introduction 1

1.1 Background 11.2 Mainstreaming Climate Risk Assessment and Adaptation 21.3 Aim of the report 31.4 Methodology 4

Chapter 2 Natural Setting 5

2.1 General 52.2 Location and topography 52.3 Climate 62.4 River network and flow regime 82.5 Physiography 132.6 Soils 162.7 Inundation land types 182.8 Aquifer 202.9 Land cover and land use 21

2.10 Fisheries 252.11 Flora and fauna 262.12 Water pollution 262.13 Char lands 282.14 Coastal zone 282.15 Marine resources 322.16 Areas of special environmental importance 32

Chapter 3 Physical Settings 40

3.1 General 403.2 Roads and Highways 403.3 Growth centers 433.4 Cyclone shelters 453.5 Ports and waterways 463.6 Irrigation infrastructure 493.7 Flood control infrastructure 53

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Chapter 4 Socio-Economic Settings 55 4.1 General 554.2 Demography 554.3 Literacy rates 574.4 GDP 594.5 Incidence of poverty 624.6 Access to safe drinking water 644.7 Major livelihood groups 654.8 Industry 664.9 Tourism 69

4.10 Areas with special economic importance 69

Chapter 5 Natural Hazards 72 5.1 General 725.2 Floods 725.3 Drought 745.4 River bank erosion 765.5 Salinity intrusion 775.6 Cyclonic storm surge 78

Chapter 6 Vulnerability to Natural Hazards 80

6.1 General 806.2 Vulnerability of people in different AEZs 806.3 Vulnerability to floods 826.4 Vulnerability to droughts 876.5 Vulnerability to cyclonic storm surge 92

Chapter 7 Institutional Settings 98

7.1 General 987.2 Institutional coordination 987.3 National government institutions 997.4 Local government institutions 1007.5 Private sector 1017.6 NGOs and CBOs 1017.7 Informal institutions 1017.8 Networking 101

References 103

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List of Tables

Table 2.1 Area of Agro-Ecological Zones 15Table 2.2 Classification of cultivable land by flood depth 18Table 2.3 Regional distribution of inundation land types 19Table 2.4 Inundation land types in agro-ecological regions 20Table 2.5 Land cover distribution 21Table 2.6 Cropped areas, irrigated areas and production in 2006-07 22Table 2.7 Region distribution of cropped areas, cropping intensities and rice

cropped areas in 2006-07 23

Table 2.8 Total catch and area productivities by sectors of fisheries for 2005-06 25Table 2.9 Major polluting industries in Bangladesh 27Table 2.10 Some basic statistics of the coastal zone 30Table 2.11 Description of coastal islands and chars 33Table 3.1 Road lengths and density 40Table 3.2 Distribution of growth centers in Bangladesh 43Table 3.3 Distribution of cyclone shelters in the coastal districts 45Table 3.4 Distribution of ports and waterways 48Table 3.5 Summary of irrigation by different modes 49Table 3.6 Irrigation by different modes in different districts 50Table 3.7 Distribution of industries in four major divisions 67Table 3.8 Average annual employment by major industry groups 67Table 3.9 Employment and production of major industries 67Table 3.10 Tourism statistics of Bangladesh 69Table 5.1 Surface and soil salinity levels 78Table 6.1 Major hazards in different physiographic units 80Table 6.2 District-wise distribution of flooding extent (%) by different types of

flood 83

Table 6.3 District-wise distribution of population affected by flood 85Table 6.4 Small farmers and rural wage labors vulnerable to very severe and

severe drought 88

Table 6.5 Small farmers and rural wage labors vulnerable to moderate drought 90Table 6.6 Population vulnerable to cyclone in high risk zones ( > 1 m surge) 94Table 6.7 Population vulnerable to cyclone in risk zones (< 1 m surge) 95

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List of Figures

Figure 2.1 Administrative units of Bangladesh 5Figure 2.2 Generalized relief contours 6Figure 2.3 Spatial and temporal distribution of temperature (2002) in Bangladesh 7Figure 2.4 Spatial and temporal distribution of rainfall in Bangladesh 8Figure 2.5 Location of Bangladesh in the GBM basins 9Figure 2.6 GBM basins and river systems of Bangladesh 10Figure 2.7 Spatial distribution of annual maximum discharge of 2, 20 and 100 year

return period 11

Figure 2.8 Spatial distribution of average annual maximum, average annual and average annual minimum discharge in major and medium rivers

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Figure 2.9 Location of Agro-Ecological Zones (AEZs) 14Figure 2.10 Map of general soil types 17Figure 2.11 Inundation land types 19Figure 2.12 Location of forests and water bodies 21Figure 2.13 Occurrence of different cropping patterns by inundation land type 24Figure 2.14 Distribution of major polluting industries among four divisions 27Figure 2.15 Coastal zone of Bangladesh 29Figure 2.16 Areas of special importance in the coastal zone 36Figure 3.1 Density of roads in Bangladesh 42Figure 3.2 Location of growth centers 43Figure 3.3 Major navigation routes classified by BIWTA 47Figure 3.4 Location map of flood control projects in Bangladesh 53Figure 4.1 Distribution of population among districts 56Figure 4.2 Distribution of population density (per km2) among districts 57Figure 4.3 Distribution of adult literacy rates among districts 58Figure 4.4 Change in sector-wise share of GDP 59Figure 4.5 District-wise change in sectoral share of GDP 60Figure 4.6 Distribution of GDP and growth rates among districts 61Figure 4.7 Poverty incidences by region 63Figure 4.8 Year-wise comparison of national poverty incidences 63Figure 4.9 Poverty incidence by occupation in 2004 64Figure 4.10 Access to safe drinking water (%) 64Figure 4.11 District-wise population (per km2) of the four livelihood groups 65Figure 4.12 District-wise percentage of four livelihood groups 66

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Figure 4.13 Marine fishing zones of Bangladesh 70Figure 5.1 Map of Flood prone areas 73Figure 5.2 Growth of flood control projects and variability of annually flooded area 74Figure 5.3 Drought prone areas in Bangladesh 75Figure 5.4 Erosion prone areas in Bangladesh 76Figure 5.5 Average dry season salinity zones in the coastal area 77Figure 5.6 Cyclone risk zone of coastal area of Bangladesh 79Figure 6.1 (a) Population vulnerable to severe and moderate floods (/km2) 82Figure 6.1 (b) Population (four major livelihood) vulnerable to severe and moderate

floods (/km2) 83

Figure 6.2 (a) Population vulnerable to very severe and severe drought 87Figure 6.2 (b) Population (four major livelihood) vulnerable to very severe and

severe drought 88

Figure 6.3 (a) Population vulnerable to high risk cyclone (/km2) 92Figure 6.3 (b) Population per km2 (four major livelihood), vulnerable to high risk

cyclone (>1m surge height) 93

Figure 6.3 (c) Population per km2 (four major livelihood), vulnerable to risk cyclone (

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Executive Summary

Bangladesh is considered to be one of the most vulnerable countries to climate change because of its geographical location and physiographic features, and low capacity to adapt to change. The country is prone to a multitude of natural hazards (e.g. floods, droughts, storm surge, salt water intrusion, river erosion, etc.) and vulnerable to the adverse impacts of future change in climatic conditions. Before addressing climate change adaptation in the context of development, it is important to recognize that todays climate already influences economic opportunities and development prospects, and that projected climate change impacts would in fact reinforce many of these baseline stresses. It is important to characterize existing vulnerabilities; future climate change will be superimposed on existing vulnerabilities. The first task of defining the present risk environment is to characterize natural, physical, socio-economic and institutional settings of the country.

Natural settings

Bangladesh is bounded by India in the west, north and east, Mayanmar in the south-east, and the Bay of Bengal in the south. Most of the country is low-lying land comprising mainly the floodplain delta of the three major rivers, the Ganges, the Brahmaputra and the Meghna, which originate outside Bangladesh and meet inside Bangladesh before discharging to the Bay of Bengal through a single outfall. Floodplains occupy 80% of the country. The land elevation increases towards north-west and reaches an elevation of about 90 meters above the MSL.

Bangladesh has a tropical monsoon climate. In general, the climate is characterized by high temperature, heavy rainfall, often excessive humidity during monsoon and marked inter and intra seasonal variation. Average annual rainfall for the country is about 2,200 mm. About 80% of the rainfall occurs during the months from May to September. There is also spatial variability of rainfall; rainfall is the lowest (1400 mm) near the western border, and highest (5500 mm) near the border in the north-east.

Flows in Bangladesh are principally controlled by how much flow is generated in the upstream catchments of the Ganges-Brahmaputra-Meghna (GBM) basins. The country is crisscrossed with an intricate network of around 200 rivers, of which 57 are international rivers originating outside the boundary of Bangladesh. The Brahmaputra has the largest flood flow followed by the Ganges and the Meghna, with a flow ratio of 4.4:2.5:1. Unlike other deltas, the seasonal variation in flow is highly skewed with abundant water during monsoon while very small flow during dry season. The country, therefore, faces two major hazards: floods during the wet season and scarcity of water during the dry season.

Bangladesh comprises three discernible broad physiographic regions: floodplains, terraces (slightly uplifted fault blocks), and hills. The broad physiographic regions are further categorized into 30 Agro-Ecological Zone (AEZ) units. Hill areas include the northern and eastern hills and occupy about 12% of the country. Terrace areas include Madhupur Tract in the center, Barind Tracts in the north-west., and Akhaura terrace in the east, occupying about 8% of the country. Floodplain areas include alluvial floodplain and estuarine areas and occupy the remaining 80% of the country.

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Bangladesh has a wide diversity of soils between and within regions, within villages, between neighboring fields and even within individual field. Broadly, the soil resource of Bangladesh could be divided into three major groups: floodplain, hill and terrace soils. The floodplain soils are alluvial deposits ranging from sandy soils deposited on higher ridges, silty clay loams on the lower ridges, and silty clays and clays in the depressions. A diversity of soils occurs in the terrace soils ranging from red to grey, deep to shallow, level to sloping, well drained to poorly drained, and from calcareous to very strongly acidic. Most have a low moisture-holding capacity, so they are easily prone to drought, and natural fertility generally is low. Hills have mainly loamy soils of shallow depth, best suited for tree crops or forest production, but not suited for the cultivation of shallow-rooted crops because of the poor water-holding capacity.

There are chars (islands and accreted lands) along the banks of the Brahmaputra-Jamuna and parts of the Ganges-Padma and the Lower Meghna. The active river floodplain occupies roughly 6% of Bangladesh, of which 40% is island chars. The island chars are inhabited by more than one million people, who are vulnerable to displacement due to river erosion.

Bangladesh has a total area of 14.7 Mha and a net cultivable area of around 8.64 Mha. The topographic position of land in relation to the monsoon season inundation, i.e. inundation land type, largely decides the land use type in the country. High land, medium high land, medium low land, low land and very low land occupy 29%, 35%, 12%, 8% and 1% of the total cultivable area, respectively. However, there are regional variations in proportions of inundation land types.

Agricultural land dominates the land cover of the country, followed by forests (including mangroves), urban and settlements and rivers and water bodies. Flood hydrology, soil and seasonal distribution of rainfall largely determine the land use including types of crops to be grown and intensity of its use. High rainfall and seasonal flooding make conditions particularly suitable for paddy cultivation; rice (the staple cereal crop) occupied about 77% of total cropped area of 13.73 Mha in 2006-07. Cropping intensity was 176% in 2005-06; however, there are substantial district-wise variations in cropping intensities.

Bangladesh is the third among the top inland fish producing nations, and also the third in inland aquaculture production. About 260 species of freshwater finfish, four species of freshwater crabs, 10 species of freshwater shrimps/prawns and 20 species of turtles have been recorded. The estuaries of Bangladesh are rich in biodiversity with 149 species of finfish, and 19 species of shrimp/prawns. In marine water, there are 442 species of fish and 11 species of marine crabs. Fisheries sector in Bangladesh represents 5.1 per cent of total GDP, but it fully employs 1.5 million rural people and provides partial employment to another 11 millions.

The coastal zone is a region of multiple vulnerabilities and opportunities. On the one hand, it is prone to severe natural hazards (e.g. cyclones, storm surges, floods, and salt water intrusion), which is compounded by high density population, with three-fourths of population representing poor livelihood groups. On the other hand, the coastal zone is the source of diversified biological (fisheries), mineral (sand, metals) and energy (wave energy) resources, is endowed with Export Processing Zones, harbors, airports, land ports and tourism complexes, sea ports (Chittagong and Mongla) and other industrial units, and contains several ecosystems of conservation values, such as the Sundarban mangrove (a World Heritage Site)

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and coral ecosystem of St Martins Island. The Sundarban is the largest single tract of mangrove ecosystem in the world, containing a considerably high floral (245 genera and 334 plant species) and faunal (453 species) diversity. The Sundarbans provides livelihood and employment to wood cutters, fishermen, honey and wax collectors, shell collectors, timber traders and workers, workers of fish drying industries, etc. The sundarbans is the major producer of honey in the country and account for about 20 per cent of the total honey production of Bangladesh.

There are many coastal islands and chars, both landward and seaward of the coastline. There are in total 60 islands: 9 located in the sea, 49 in the estuary and 11 in the coastal rivers. In addition, 65 charlands are identified. The size of the islands and chars varies between 2 and 77,000 ha; the three largest ones are Hatiya, Sandwip and Bhola. Only half of these islands and chars are somewhat protected; 40% are populated by less than 5,000 people. Because of the instability of the land, island dwellers are often forced to move from one place to another. Families shifting 10-15 times over 10 years is not uncommon.

The country is rich in marine resources. The bulk of the countrys exploitable fisheries extend largely to the 50 m mark (representing 37,000 km2) in the Exclusive Economic Zone (EEZ). Marine capture fisheries is an important source of output, employment and livelihood in the coastal regions. About 7.3 million people live in the coastal marine fishing villages of which 22% have taken fishing as their major occupation.

Recognizing the gradual depletion of the ecosystems and the need for the protection of natural system, Government of Bangladesh created and implemented laws and regulations to declare Protected Areas at different locations. These include reserved forests in sundarbans in the districts of Bagerhat, Khulna and Satkhira and non-mangrove forests in Barguna, Bhola, Chittagong, Coxs Bazar, Feni, Lakshmipur, Noakhali, and Patuakhali districts, 7 wildlife sanctuaries (five in the coastal zone and two in the non-coastal zone), one game reserve in the coastal zone, 8 national parks (two in coastal zone and six in non-coastal zone), three Ramsar sites, 8 ECAs (ecologically critical areas), 3 world heritage sites, 204 sq nautical mile of marine reserve, and one ecopark (with two others in the pipeline).

Physical settings

Bangladesh is covered by a large road and highway network, most of it traversing through the flood plains of the country. There were nearly 21,000 kilometers of national and regional highways in 2000 and nearly 250,000 kilometers of upazila, union and village roads in the whole country, the road density being as high as 1.85 km/km2. The coastal zone has a higher density of roads (2.03 km/km2) than other areas (1.85 km/km2), indicating a good development of road network in the coastal zone.

There are over 1700 growth centers, including hats and bazaars, in the country. On average, there are 1.5 growth centers per 100 km2 centers. The highest density occurs in Chittagong (5.87) followed by Naogaon (4.87). The other regions where the development of growth centers has been high are Bogra, Maulvibazar, Pabna, Netrokona, Patuakhali and Habiganj.

Cyclone shelters are constructed to provide refuge to the exposed population during storm floods, and also intended for multi-purpose use as school and community center. Presently there are a little over 2,100 shelters in 15 of the 19 coastal districts that can accommodate

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only 27% of the people at risk. The National Water Management Plan (NWMP) proposes 775 multi-purpose shelters for 1.72 million people and 1,369 killas (raised earth mounds) for livestock over the next 15 years. One of the planning issues is how to allocate shelters and killas equitably among competing areas.

A dense network of rivers, canals and creeks serves large parts of the country and provides a cheap means of transport. Based on plying on large (4 tons) boats, the total length of waterways in the monsoon season exceed 6000 km, which shrink to about 3800 km at the end of dry season. If small dingis and boats are considered, the total length in the monsoon season may exceed 24,000 km. Country boats alone offer 60% of all employment in the transport sector. Bangladesh Inland Water Transport Authority (BIWTA) classifies four major navigation routes based on the level of service to be guaranteed taking into account the economic importance of the river as well as the technical and financial capacity to maintain the level of service. Over the years, BIWTA has developed 11 major inland river ports, 5 ferry terminals, and over 300 launch ghats at important locations. The inland ports and landing ghats serve as feeder ports to the two seaports of the country. The Chittagong port is the main sea port of Bangladesh, the second important sea port being at Mongla.

Irrigation in Bangladesh is divided into two categories: minor and major irrigation. The common methods of minor irrigation technology are power pumps (LLPs) for pumping irrigation water from surface source and pumping of groundwater using STWs and DTWs. In some parts of the country, irrigation is carried out by gravitational flow through major irrigation projects. Out of 8,64 Mha net cultivable area, 4.88 Mha was irrigated in rabi season in 2007, of which 4.73 Mha was irrigated by DTWs, STWs and LLPs, 0.014 Mha by traditional methods, and 0.137 Mha by gravity flow. Out of total irrigated area, groundwater accounted for 80.60%, while surface water accounted for the remaining 19.40%. A total of 29,177 DTWs, 1,202,728 STWs and 1,072,936 LLPs were in operation in 2007 (BADC, 2007).

In order to protect agricultural floodplains, there has been a steady growth of flood control and drainage projects in Bangladesh since mid 60s. Generally, flood control projects can be classified into four major types: FC (Flood Control) projects; FCD (Flood Control and Drainage) projects; FCDI (Flood Control, Drainage and Irrigation) projects; and D (Drainage) projects. Bangladesh Water Development Board (BWDB) has developed 24 FC projects, 241 FCD projects, 82 FCDI projects and 104 D projects over the years covering benefitted areas of 0.248, 2.36, 1.85 Mha, and 0.77 Mha, respectively. Besides, 46 submersible embankment (FC) projects in the northeast region have been developed covering an area of 0.29 Mha. No new schemes have commenced since 1995, other than partial flood protection schemes in the northeast region.

Socio-economic settings

The total population of the country is 123.15 million, male population being 62.74 million (51% of total) and female 60.41 million. Average population density of the whole country is 839 per km2, with the densest population areas centering on Dhaka district, where it averages 5,643 people per km2, followed by Comilla (3,988 /km2), Jamalpur (2,923 / km2), and Naogaon (2467 / km2). The total population in the coastal region amounts to 35.08 million, male population being 17.9 million and female 17.1 million. They are 28% of the total population of the country. The average density of population per km2 is about 743, which is

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well below the national average. About 1/3rd of the total coastal population live in the exposed coasts.

Adult (15+ years) literacy rate is highest in Dhaka (59%) followed by Pirojpur (54%). Districts of Sunamganj (24%), Kishoreganj (25%), Jamalpur (23%) and Coxs Bazar (23%) have much lower literacy rates than the national average. The male literacy rate is higher than the female literacy rate in all districts with national average of 43% and 24%, respectively. The adult literacy rate in the coastal zone is higher than the national average (both sexes 40%, male 49%, female 39.

Evolution of Bangladesh economy's structure since independence in 1971 has followed the path typical of developing countries, with a progressive reduction in agriculture's share of Gross Domestic Product (GDP) from 50% in 1972-73 to 20% in 2006-07, an increase from 38% to 53% in the services sector share and an increase in the industrial sector's share, from 13% to 27%. For most of the period from independence in 1971 to the 1990s Bangladeshs economic growth was modest, at about 4% per year (3.5% in the 1980s and 4.8% in the 1990s). Since the mid-1990s till mid-2000s, however, annual growth in GDP increased to an average rate of 6% (5.3% in 2003, 6.3% in 2004, 5.96% in 2005 and 6.63% in 2006). The total GDP of the country in the financial years 2004, 2005 and 2006 were 3330, 3707 and 4157 billion taka, respectively, at current market prices.

Poverty is the central socio-economic issue in Bangladesh. Overall, the rural poor tend to be landless, live in remote areas, and have inadequate access to basic infrastructure and services. Urban poverty is associated with limited employment opportunities, poor health, inadequate water supply and sanitation facilities, and frequent eviction of squatters by the authorities. Athough there has been considerable progress, as manifested in decrease in poverty incidence by 10% during 1990-2000, one of the fastest rates of decline recorded worldwide, still about 42% of the population are stricken by poverty. The national average poverty incidence has followed the previous decreasing trend, more significantly for urban population. The national average poverty indices in 2004 were 0.379 and 0.433 for urban and rural population, respectively, compared to 0.433 and 0.449 in 1999. In 2004 the highest poverty was observed in Rajshahi division (0.616), a significant jump in poverty index in 5 years, and the lowest in the Sylhet division (0.284), a further reduction from 1999. However, these figures should not obscure the fact that the absolute numbers offer a more vivid picture of the scale of the problem.

Bangladesh has made significant progress in extending access to water supplies, yet several districts (especially Khulna, Barisal and Satkhira) in the coastal region lag behind national averages. In the last decades, public health in the coastal regions had greatly benifitted from the massive shift from surface to groundwater sources for domestic water supply. At present, the situaton is reversing; in addition to reduced availability of safe drinking water because of arsenic pollution, people now have to deal with saline groundwater, especially at the end of dry season. The highland population in the eastern hills region is subject to severe scarcity of domestic water.

Four major livelihood groups in Bangladesh who account for large shares of the poor population are small farmers, fishermen, rural wage labor and urban wage labor. Rural wage labors (mainly agricultural laborers) constitute the largest livelihood group in the country in terms of density as well as number. Small farmers stand second. Among the non-farmers

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(whose principal occupation is not agriculture), fishers are the single largest group. In the coastal zone, the districts of Bhola, Satkhira, Khulna and Jessore have higher concentrations of agriculture laborers than other districts.

Industry is a major economic sector in Bangladesh. Among the industries that have been set-up, ready-made garments, cotton textile, food and beverages, sugar, leather, pharmaceuticals, fertilizer, wood product, iron and steel, ceramic cement, rubber and plastic product and chemicals are important. About 47% of the industries are located in Dhaka division, followed by 20% in Rajshahi division, 17% in Khulna division and 16% in Chittagong division. The major industries employed about 2.46 million in 2001-02. The garments industries (manufacturing of textiles and wearing apparels) provide the largest share of employment (74.5% of total) and the largest share of the production value (50% of total). Manufacturing sector contributes about 17% of the GDP. Growth rate of manufacturing sector is dominated by ready-made garments.

Bangladesh is bestowed with the bounties of nature, and hence tourism is another important economic sector. Bangladesh earns substantial foreign currency from tourism; the foreign currency earned in 2007 was more than 5 billion taka.

Some areas that offer special services and maintain core socioeconomic functionality such as sea ports, land ports, air ports and export processing zones, have provided a special status to facilitate economic activities under various laws and regulations. The countrys Exclusive Economic Zone (EEZ) stretches 714 km along the coastline and comprises 164,000 km2. The bulk of the countrys exploitable fisheries extend to 50 m mark, representing 37,000 km, while the industrial trawl fishery exploits fishery resources to a depth of 100 m. Besides, marine fishing zones have been demarcated according to fishing possibilities. The two sea ports at Chittagong and Mongla are also among the areas of special economic importance. There are 14 land ports, 10 airports (of which 3 are international), and 8 eight Export Procesing Zones (EPZs) in the country.

Natural hazards

In Bangladesh, principal natural hazards that have occurred in Bangladesh over centuries include floods, droughts, cyclones, river erosion, and salt water intrusion. Cyclones have the most dramatic consequences. Riverbank erosion is in second place, not in terms of deaths, but in terms of the process of impoverishment and landlessness of the many people affected. The number of deaths during monsoon floods, even during extraordinary events, is comparatively small. Drought is a "creeping phenomenon"; the effects of drought accumulate slowly over a considerable period of time, and may linger for years after the termination of the event.

Flood in Bangladesh is an annual phenomenon; about 20% of its area is inundated by overflowing rivers during monsoon in a normal flood year, about 35% in a moderate flood year, and more than 60% in a major flood year. The principal sources of floods are the river floods from the major river systems, the Brahmaputra, the Ganges, and the Meghna, local rainfall floods resulting from runoff of high intensity and long duration rainfalls that can not be drained because of high outfall water levels, flash floods from the adjacent hills in India in the pre-monsoon months of April and May, tidal floods in areas adjacent to estuaries and tidal rivers in the southwest and southcentral parts of the country twice a day due to astronomical tide from the Bay of Bengal, and occasional cyclonic storm-surge floods due to tropical cyclones in the Bay of Bengal during April to June and September to November. River and

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rainfall flood are frequently aggravated by the backwater effect from the sea and the timing (synchronization) of peak flows in the major rivers.

Drought is a common hazard for the rainfed cultivation in Bangladesh. Past droughts have typically affected about 47% area of the country and 53% of the population. Bangladesh experience long spells of dry weather and moderate to severe droughts are spread over a region of 5.46 million ha in the districts of Rajshahi, Natore, Chapai Nawabganj, Rangpur, Dinajpur, Bogra, Kushtia, Jessore and Dhaka. Aman cultivation suffers from periodic drought conditions from long spells of rainless days ranging upwards from two weeks. Drought conditions are also observed in early pre-Kharif months, affecting Boro and wheat cultivation.

Important secondary consequences of climatic hazards include riverbank, char (river and deltaic islands), and coastal erosion. Erosional processes along the rivers render some millions of people landless. Out of the 462 administrative units in the country, 100 are subject to some form of riverbank erosion, of which 35 are serious, and affect about 1 million people on a yearly basis. The towns of Sirajganj and Chandpur are under constant threat from the Jamuna and the Lower Meghna, respectively. The Meghna estuary is a highly dynamic place of erosion and accretion. Erosion is also a problem in inland coastal rivers in Barisal, Patuakhali, Bhola, Barguna, Jhalakathi and Pirojpur districts of the Barisal division, resulting in hundreds of families homeless and shelterless.

Water and soil salinity are normal hazards in many parts of the coastal area. In the southwest region, surface water salinity has been aggravated by the reduction in dry-season flows entering the Gorai distributaries, following the diversion of the Ganges flow upstream of the border. Salinity now reaches as far as Khulna, creating problems to normal agricultural practices and affecting the supply of clean water for industrial use. River water salinity has also important implications for the natural environment, such as functioning of the Sundarban ecosystem, sedimentation rates in tidal rivers, and human health. A total of 1.65 million ha of land (70%) out of 2.34 million is affected by different degrees of soil salinity within Khulna and Barisal divisions. It traditionally restricted the cultivation of Aus, Boro (HYV) and dry season rabi crops. There is a seasonally salinty interface, with the threshold limit for agriculture moving inland in May in the southern part of the coastal region.

Tropical cyclones accompanied by storm surges are one of the major disasters in Bangladesh. The Bay of Bengal is a favourable breeding ground of these cyclones. When minimum death tolls over 5000 are considered, it turns out that Bangladesh is the worst sufferer of all cyclonic casualties in the world, with a death toll of about 53% of the global. The high number of casualties in Bangladesh is due to the fact that cyclones are always associated with storm surges. Storm surge amplifications on the Bangladesh coast are facilitated by a number of factors, including the shallow water in the north Bay, the northward-converging nature of the Bay, and high astronomical tides.

Vulnerability to natural hazards

Severe and moderate river flood prone areas are mainly located in the floodplains of the major rivers (e.g. Brahmaputra-Jamuna, Meghna estuarine and low Ganges river floodplains), the Haor basin and the lower Atrai basin, and areas prone to severe and moderate flash floods include mainly the northern and eastern piedmont plains and Chittagong coastal plains. Drought prone areas are mainly located in the western part of Bangladesh, with very severe

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areas concentrated in the Barind Tract and adjacent high Ganges river floodplain areas. Active floodplains of the major rivers, the Teesta, the Brahmaputra and the Ganges, and middle and young estuarine floodplains of the Meghna are the major areas prone to river erosion. High risk and risk areas for cyclone are located within the exposed areas of the coastal zone (Ganges tidal plain, Meghna estuarine floodplain and Chittagong coastal plain). Major salinity intrusion takes place in the Ganges tidal plain, with the salinity front extending into the high Ganges river floodplain and Gopalganj-Khulna Beels in some dry months. Salinity intrusion is limited to much shorter distances from the coastline in young Meghna estuarine floodplain and Chittagong coastal plain.

About 45.5 million people are estimated to be exposed to severe and moderate floods (including river flood, flash flood and tidal flood), of which 22 millions are male and 23.5 millions are female. Districts with higher population vulnerable to flood are Chittagong, Comilla, Sylhet, Sirajganj, Khulna, Noakhali, Faridpur, Pabna, Patuakhali, Bogra, Bagerhat, Satkhira, Sunamganj, Bhola, Dhaka, Kurigram and Pirojpur, with population varying from 0.1 to 3.4 millions. Floods affect about 8 million small farmers, espcially in the districts of Khulna, Munshiganj, Faridpur, Bogra, Sirajganj, Noakhali, Bagerhat, Satkhira, Jhalokathi, Rajbari, Patuakhali, Chittagong, Lakshmipur, Sylhet and Barguna, about 10 million rural wage laborers, especially in the districts of Sylhet, Sirajganj, Chittagong, Khulna, Sunamganj, Satkhira, Noakhali, Faridpur, Munshiganj, Bhola and Bagerhat, about 0.95 million fishermen, mainly in the districts of Bhola, Bagerhat, Sylhet, Satlhira, Chittagong, Coxs Bazar, Sunamganj, Bargguna and Patuakhali, and about 0.83 million urban wage laborers, mostly concentrated in the districts of Bogra, Chittagong, Sylhet, Faridpur, Dhaka, Narail and Khulna.

As far as per centage of area in each district is concerned, very severe and severe drought are prominent in the districts of Joypurhat, Nawabganj, Naogaon, Rajshahi and Dinajpur, with area varying from 91 to 55% of respective district areas. The major districts under the influence of moderate drought are Chuadanga, Meherpur, Jhenaidah, Panchagarh and Jessore, with area varying from 88 to 78% of respective district areas. About 2 million small farmers and 2.4 million rural wage laborers are vulnerable to very severe to severe Kharif drought, majority of whom live in the districts of Joypurhat, Nawabganj, Naogaon, Rajshahi and Dinajpur. Small farmers and rural wage laborers exposed to moderate drought total 6 and 6.6 millions. Majority of small farmers live in the districts of Chuadanga, Jessore, Tangail, Bogra and Gazipur. Majority of rural wage laborers live in the districts of Chuadanga, Satkhira, Dinajpur, Bogra and Jessore.

About 6.2 million people in 12 districts (Bhola, Coxs Bazar, Barguna, Patuakhali, Noakhali, Bagerhat, Khulna, Lakshmipur, Feni, Pirojpur and Barisal) are estimated to be at High Risk from cyclonic surges. Addition of a further 2.3 million in 14 districts (Barguna, Lakshmipur, Pirojpur, Patuakhali, Bagerhat, Barisal, Khulna, Coxs Bazar, Satkhira, Chittagong, Feni, Noakhali, Bhola and Bandarban) at Risk results in a total at-risk population of 8.5 million. In terms of area under high risk, Bhola, Coxs Bazar, Barguna, Patuakhali and Noakhali rank first, second, third and fourth, fifth, respectively. However, in terms of population exposed to High Risk, Bhola, Chitatgong, Noakhali, Coxs Bazar and Patuakhali rank first, second, third, fourth and fifth, respectively.

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1. Introduction 1.1 Background Bangladesh, one of the Least Developed Countries (LDCs), is struggling to cope with current climatic conditions and the impacts of extreme climatic events on livelihoods and food security. To make matters worse, the country is considered to be one of the most vulnerable countries to climate change because of its geographical location and physiographic features, and low capacity to adapt to change. A setting in the tropics, in the floodplain delta of the three major river basins - the Ganges, the Brahmaputra, and the Meghna, and extensive low floodplain topography with a low lying coast line, has rendered the country prone to a multitude of natural hazards (e.g. floods, droughts, storm surge, salt water intrusion, river erosion, etc.) and vulnerable to the adverse impacts of future change in climatic conditions. With an economy highly dependent on agriculture, the lives and livelihoods of people are always under threat. The societal exposure to such risks is further enhanced by Bangladeshs very high population and population density. With a population of about 140 million, Bangladesh is one of the most densely populated countries of the world (BBS, 2006).

Global warming induced changes in precipitation and temperature is already happening in different geographical regions, influencing patterns and intensities of the natural hazards. Changes in the climate are likely to take place more rapidly over the next few decades, as predicted by different climate model simulation (IPCC, 2007). It is anticipated that increased rainfall will result in increased flooding during monsoon, increase in temperature and less rainfall during the dry period will create more drought conditions, and magnitude, intensity and frequency of natural disasters (e.g. droughts, floods and storm surges) will increase. The impact of any change in the length of the monsoon would be significant. If the monsoon is shortened, soil moisture deficits in some areas might get worse, while prolonged monsoons might cause frequent flooding and increase inundation depths. Besides, the anticipated sea level rise in the Bay of Bengal would further compound the problem in Bangladesh through coastal submergence, enhanced drainage congestion in the floodplain and increased salt water intrusion.

Such changes in climate will ultimately affect the life and livelihoods of the people. By and large, any change in the availability of water resources as a consequence of climate change could have a substantial effect on freshwater resources, coastal zone, agriculture, fishery, ecosystem, biodiversity, navigation, salinity control and safe drinking water supply. The coping ability or adaptive capacity of people to the effects of anticipated climate change depends on a variety of economic, social and technological factors such as infrastructure, access to and the distribution of resources and management capabilities. Poor countries and people tend to be particularly vulnerable to deviations from average climatic conditions and climatic extremes (OFDA/CRED, 2006). In Bangladesh, the vulnerability to climate change increases manifolds since the country has low adaptive capacity to climate change because of the widespread poverty, with 34% of the people living below the national poverty line (World Bank, 2003) and about 77% of the high density population living in the rural areas (BBS, 2003). High population density increases vulnerability to climate change because more people are exposed to risk and opportunities for migration within a country are limited.

Many developing countries are already experiencing increasing stresses from climate variability and extremes, and will continue to experience the same increasingly in the future

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as climate change progresses. Many sectors providing basic livelihood services to the poor are not able to cope even with todays climate variability and stresses (Sperling, 2003). Many projected climate change impacts (including sea level rise, higher temperatures, evapo-transpiration losses, enhanced monsoon precipitation and run-off, potentially reduced dry season precipitation, and increase in cyclone intensity) would in fact reinforce many of these baseline stresses that already pose a serious impediment to the economic development of Bangladesh (Agrawala et al., 2003). Before addressing climate change adaptation in the context of development, it is important to recognize that todays climate influences economic opportunities and development prospects. It is important to characterize existing vulnerabilities because the impacts of climate change, and the vulnerability of poor communities to climate change, vary greatly.

1.2 Mainstreaming Climate Risk Assessment and Adaptation

Responding to climate change is a necessity for all countries prone to climate hazards. The climate change impacts are exerting pressure on the development process, putting the interventions to risk on one hand and threatening the production system on the other. As climate change impacts development, it has to be dealt while pursuing development through national development planning. In line with this understanding, a country framework was formulated to mainstream climate risk management and adaptation in development (DoE, 2006). The framework will be operationalized by establishing a mechanism that will facilitate a systematic interweaving of national development planning and implementation with adaptation to climate change and climate risk management over time. This will help ensure that national development is resilient to climate change and its impacts in such a way that the lives, livelihood and well being of its people are sustained in the long run.

The basic components of the proposed country framework are:

(i) Defining risk environment. The first task is to define and determine the risk environment for both current and future climate risks. The definition of climate risk environment need to encompass the following:

Natural setting: A thorough knowledge-based characterization of natural conditions or setting will enable people to understand the dynamics of impacts of climate change over time and help identify appropriate measures to manage climate risks (McCarthy et al., 2001).

Physical setting: Mapping and characterizing physical infrastructure are necessary to understand the exposure to climate induced phenomena, performance capability under changed conditions, and overall risks of these infrastructures to climatic hazards.

Socio-economic setting: Socio-economic conditions of an individual, a household, a community, and a society (or even the whole country) determine how the contexts of vulnerability will change underlying risks due to change in exposure to any hazard.

Institutional setting: Institutions, including the current policy regime, help identify part of the social and financial strengths of a vulnerable society (community/households/ individuals). The interactions of institutions with the livelihood capital assets (LCAs) and climate driven vulnerability contexts provide information on livelihood outcomes of the society.

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When the present day risk elements are overlaid on climate perturbations in any point in future, it would portray future risks under climate change. However, future conditions will be a function of changed conditions in all four of the above mentioned settings. If there is any significant change, it may need to be flagged based on trends, projections and expert judgments. Defining future risks would involve analysis of future (perceived or model based) climatic scenarios. Additional risks to livelihood conditions as a result of the changed scenario need to be assessed through a participatory approach; only the vulnerable themselves know how differently their risk perception will change under a defined change in climate system (Ahmed, 2004).

(ii) Responding to climate change: enabling processes and actions. Responses do not necessarily depend on specific planning or firm actions, but also on enhancing human and institutional capacity, preparing communities through social communication of risks and responses and demonstration and propagation of good practices (DoE, 2006). It will involve formulation of micro-level risk reduction action plans following participatory processes (the same processes which have been carried out for identification of risks) as well as integration across sectors and scales, ideally at community levels, identification of climate-related risks in development plans mostly applicable at meso- and regional scales, social communication of micro-level climate risks such that every member of the community are well aware of them, capacity building at various tiers and across sectors through different means (e.g. raising awareness through information, providing orientation, formal and informal training, continued education, etc.), demonstration of good practices for adaptation that could be replicated at other places of the country having similar settings, and implementation of the adaptive responses.

(iii) Institutional facilitation. Adaptation measures, after thorough processes of participatory analysis and subsequent identification, can be implemented with an appropriate institutional enabling environment. Institutional architecture should encompass both local through to the national scale institutions as well as national to global scale institutions. Global response to adaptation has to be taken into consideration and benefit from the global response in terms of policy guideline, technology, knowledge and information and all other instruments developed so far to support adaptation. In absence of an effective global institutional architecture for adaptation, each country should focus on creating its own enabling policy environment to advance adaptation. Realizing the fact that adaptation measures should be complementary to development strategies of the country, each adaptation strategy or option should ideally be previewed within development-oriented policy regime prevailing over the country. Three important aspects in the process of creating enabling policy regime are policy analysis, identification of policy gaps, and policy adjustment.

1.3 Aim of the Report

This report is an attempt to develop a base document characterizing the country settings, including natural setting, physical infrastructure there in, socio-economic conditions and prevailing environment, and hence is expected to serve as a base document to locate, identify and characterize climate risk environment in the backdrop of climate change and variability. In essence, this addresses the first task of the effort on mainstreaming climate change and adaptation, which is defining the present day risk environment.

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The hazards and vulnerability maps presented in the report are expected to be very useful to the users and stakeholders. Data and information available in the report can be used to develop climate change/ composite climate change hazard and risk maps in the next phase, which will provide a better understanding regarding the overall vulnerability of a group of people under climate change in a given location, and in turn will help identify what needs to be done in order to reduce peoples vulnerability and which specific context of vulnerability needs to be addressed on a priority basis in order to approach towards adaptation.

1.4 Methodology

The report draws data, information and maps from a good number of published documents and different organizational sources. A number of elements are presented that help define the natural setting of the country. A number of physical/infrastructural settings are characterized and mapped. Some important socio-economic indicator maps are presented. Based on published secondary data, major vulnerable livelihood groups in each district are classified and results of an analysis of the vulnerabilities of different groups of population to various climatic hazards are presented.

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2. Natural Setting

2.1 General

Understanding the dynamics of the impacts of climate change over time and identifying appropriate measures to manage climate risks require a thorough knowledge-based characterization of natural condition/setting (McCarthy et al., 2001). There may be a large number of elements which help define natural conditions. The following are most common indicators that describe natural conditions: physiology, proximity to the sea, landscape and terrain, watersheds, land type characteristics, land elevations, land cover, land use, state of land degradation; soil quality, major crops and cropping patterns, forest cover, ecosystems and ecosystem health, river network and flow regime, tidal dynamics, erosion and accretion (morphological) processes, humidity, temperature regime, surface and groundwater (availability and quality), precipitation pattern, etc. (DOE, 2006). This chapter includes characterization of several elements deemed important in the context of Bangladesh.

2.2 Location and Topography

Bangladesh stretches between 20034N and 26033N latitudes and 88001E and 92041E longitudes. The tropic of the cancer passes over Bangladesh. It has an area of approximately 144,900 km2 bounded by India in the west, north and east, Mayanmar in the south-east, and the Bay of Bengal in the south. The Himalayas is close to the northern border of Bangladesh. Three major rivers- the Ganges, the Brahmaputra and the Meghna meet inside Bangladesh before discharging to the Bay of Bengal through a single outfall. Most of the country is low-lying land comprising mainly the floodplain delta of these mighty rivers. Administratively, the country is divided into 6 divisions, 64 districts and 490 thanas. There are four metropolitan areas including the capital city: Dhaka, Chittagong, Khulna and Rajshahi. Administrative regions (Sixty-four Districts) of Bangladesh are shown in Figure 2.1. This figure will serve as the index map in this report to indicate an area. Figure 2.1 Administrative units of Bangladesh

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A generalized relief contour map is shown in Figure 2.2. It is seen that most of Bangladesh consists of extremely low and flat land. Dhaka, the capital city (about 225 km from the coast) is within 8 meters above the Mean Sea Level (MSL). The land elevation increases towards north-west and reaches an elevation of about 90 meters above the MSL. The lowest part is the coastal tidal land while the highest areas are the hill tracts in the eastern and Chittagong regions. The floodplains occupy 80% of the country. Mean elevations range from less than one meter on tidal floodplains, 1 to 3 meters on the main river and estuarine floodplains, and up to 6 meters in the Sylhet basin in the north-east (Rashid 1991). Only in the extreme northwest are elevations greater than 30 meters above the mean sea level. The northeast and southeast portions of the country are hilly, with some tertiary hills over 1000 meters above MSL.

2.3 Climate

Bangladesh has a tropical monsoon climate. In general, the climate is characterized by high temperature, heavy rainfall, often excessive humidity during monsoon (June to September) and marked inter and intra seasonal variation.

Temperature: The mean annual temperature is about 250C within the country. Mean monthly temperatures range between 180C in January and 300C in the months from April to May. The highest and lowest temperatures throughout the year range between 430C and 40C with the exception in the areas near the coast where the range is narrower. The temporal and spatial distribution of temperature is presented in Figure 2.3.

Sunshine hours: Except a little variation in the bordering areas in the east and the coastal fringe, day-length and sunshine hours throughout the whole country are in general almost the

Figure 2.2 Generalized relief contours (Source: Harza, 1986)

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same. Day length at Dhaka varies from 10.7 hours in December to 13.6 hours in June. Sunshine at Dhaka ranges from 5.4-5.8 hours/day in the monsoon season and 8.9-9.1 hours/day in the winter (from December to February) and pre-monsoon (from March to May) seasons.

Wind: The wind direction is mainly south-west and south-east during the pre-monsoon and monsoon seasons and from between north-west and north-east during the post-monsoon (from October to November) and winter seasons. The advent of occasional Norwesters with velocity of 50-100 km/hr changes the wind direction in the pre-monsoon season. Tropical cyclones from the Bay of Bengal with high velocity of more than 115 km/hr are liable to hit the coastal areas in the pre-monsoon and post-monsoon seasons.

Humidity: The humidity is relatively high throughout the year. It is over 80% during the months from June to September, i.e., the monsoon months. The humidity is around 58% in most of the western areas of Bangladesh in March and April and in the eastern areas in January, February and March.

Evaporation: Evaporation rates range from about 50-70 mm per month in the dry season to 100-175 mm per month in the pre-monsoon season. In the monsoon, they are generally about 100-125 mm. Annual potential evapo-transpiration rates (modified Penman) range from about 1,180 mm in the north-east to 1,285 mm in the centre-west. Rainfall everywhere exceeds evapo-transpiration rates in the monsoon season and for the year as a whole, even in dry years. However, evapo-transpiration rates exceed rainfall during winter and in the first part of the pre-monsoon season. Evapo-transpiration rates also exceed rainfall, of course, during droughts, most significantly during the pre-monsoon season when temperatures and evaporation rates are highest (Brammer, 2002).

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Figure 2.3 Spatial and temporal distribution of temperature (2002) in Bangladesh (BMD data)

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Rainfall: Rainfall within the country is mainly caused by the South-Westerly-Trades known as the monsoon, during the months of June to September. The two other sources of rainfall are the western depressions of winter which cause rainfall mainly from the end of January to the end of the February, and the Norwesters (the early summer thunderstorms), which cause rains mainly within the first week of May. Average annual rainfall for the country is about 2,200 mm. About 80% of the rainfall occurs during the months from May to September. The isohyetal pattern of the average annual rainfall is shown in Figure 2.4. The mean annual rainfall is the lowest (1,400 mm) in Rajshahi zone near the western border. The advancement of isohyets is towards the north, east and south reaching more than 2,500 mm in the extreme north-west, near and within the northern and eastern hills and near the coasts, and exceeding 5,500 mm near the border in the north-east. There is a wide variability of rainfall from year to year. Again, distribution of rainfall within the year is highly skewed (Figure 2.4). Rainfall during the dry season is negligible.

(a) Isohyetal pattern of average annual rainfall (b) Average monthy rainfall distribution (in cm) (BMD data: 1982-2001)

Figure 2.4 Spatial and temporal distribution of rainfall in Bangladesh

2.4 River Network and Flow Regime

Being a lower riparian country surrounded by hills on its three sides (Figure 2.5), flows in Bangladesh are principally controlled by how much flow is generated in the upstream catchments of the Ganges-Brahmaputra-Meghna (GBM) basins (Figure 2.6a) from orographic rainfalls coupled with snowmelt in the Himalayas. The total catchment area stands at 1.75 million km2 of which about 93% are located outside the country. According to Rashid (1991), about 1.18 million cubic meters of water flow annually to the sea, of which 1.07 million cubic meters or 91 per cent enters Bangladesh from India. The country is

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crisscrossed with an intricate network of around 200 rivers, of which 57 are international rivers originating outside the boundary of Bangladesh as shown in Figure 2.6b. Among them 54 rivers bring inflows from India including the three major ones, the Ganges, the Brahmaputra and the Meghna. For water management purposes, the entire country has been divided into eight hydrological regions (WARPO, 2001a).

A remarkable aspect of the river system is that all the rivers, except those in the Chittagong sub-region, are hydraulically linked to each other, all rivers being either tributaries or distributaries of the three major river systems. Hence, the flow hydraulics is dominated by these three major rivers. This is also illustrated in Figure 2.7, which shows the spatial distribution of annual maximum flood discharge of 2, 20 and 100 year return periods in major and medium rivers. The river systems carry enough water from outside the country each year to inundate the catchment inside the country with 6 meters of water (Chowdhury et al., 1997).

The Brahmaputra has the largest flood flow followed by the Ganges and the Meghna, with a flow ratio of 4.4:2.5:1. Around 54 per cent (598.908 km) is contributed by the Brahmaputra, 31 per cent (343.932 km) by the Ganges and nearly 15 per cent (162.772 km) by the tributaries of the Meghna and other minor rivers. The combined discharge of the three main rivers is among the highest in the world. Peak discharges are of the order of 100000 m/s in the Brahmaputra, 75000 m/s from the Ganges, 20000 m/s in the upper Meghna and 160000 m/s in the lower Meghna. The major river systems discharge about 1,42,000 m3/s into the Bay of Bengal at peak periods (Rahman et al., 1990).

Figure 2.8 shows the spatial distribution of average values of annual maximum, annual average and annual minimum discharges. This illustrates that unlike other deltas, the seasonal variation in flow is highly skewed with abundant water during monsoon while very small flow during dry season. It is estimated that the ratio between the discharges of the dry and monsoon for the Ganges River is 1:6 (Mirza and Dixit, 1997). Approximately 85% of the mean dry season stream flow is found in the Ganges-Brahmaputra-Meghna (GBM) rivers. Smaller regional rivers carry the remaining 15%. The country, therefore, faces two major hazards: floods during the wet season and scarcity of water during the dry season. The hydrodynamic characteristics during flood flow in alluvial rivers in Bangladesh are quite different from that during low flow (Chowdhury et al., 1997; Salehin et al., 2007).

Because of the great disparity between the monsoon floods and the low flow during the dry season, the manageable surface water resources are considered as equal to 80 per cent of the dependable flow in March. In terms of water availability, March is the critical month in Bangladesh. Surface water resources are used extensively for dry season irrigation.

Figure 2.5: Location of Bangladesh in the GBM basins (Source: World image layer, ArcGlobal data, ESRI)

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Figure 2.6: GBM basins and river systems of Bangladesh

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48

52

54

51

55

57

5

4

3

2

1

6

7

8

91011

13

12

14

1516

1720

21

1819

22

23

24

25

2627 28 29 30

3132 33

38

37

3634 35

39

40

45

56

53

42

5049

44

47 4346

48

52

54

51

55

57

Bra

hmap

utra

Riv

er

Ganges River

Meg

hna

Rive

r

Dhaka

Lower M

eghnaRiver

Padma River

NW

NC

SW

EH

NE

SE

SC

RE

Border riverBorder river

b. River systems of Bangladesh

India

Nepal

Bangladesh

Ganges Basin

Meghna Basin

Brahmaputra BasinBhutan

India

Nepal

Bangladesh

Ganges Basin

Meghna Basin

Brahmaputra BasinBhutan

a. GBM basins

NW: NorthwestNC: NorthcentralNE: NortheastSW: SouthwestSC: SouthcentralSE: SoutheastEH: Eastern HillsRH: Rivers and Estuaries

China

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Figure 2.7: Spatial distribution of annual maximum discharge of 2, 20 and 100 year return period (Source: Chowdhury et al., 1997)

12

Figure 2.8: Spatial distribution of average annual maximum, average annual and average annual minimum discharge in major and medium rivers (Source: Chowdhury et al., 1997)

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2.5 Physiography

Bangladesh comprises three discernible broad physiographic regions: floodplains, terraces (slightly uplifted fault blocks), and hills. Each of these regions exhibits its own geo-morphological characteristics. The broad physiographic regions are further categorized into 30 Agro-Ecological Zone (AEZ) units as shown in Figure 2.9. The area of the individual units is shown in Table 2.1.

Hill areas include the northern and eastern hills and occupy about 12% of the country. These are underlain by Tertiary and Quaternary sediments which have been folded, faulted and uplifted, then deeply dissected by rivers and streams. There is an overall pattern of long, linear ridges running approximately north-northwest to south-southeast with the highest elevation as high as 900 m above the MSL.

Terrace areas include Madhupur Tract in the center, Barind Tracts in the north-west., and Akhaura terrace in the east. Terraces occupy about 8% of the country. These areas are not true alluvial terraces but are almost flat surfaces appearing above the recent deposits. The Madhupur Tract and the Akhaura terrace are closely dissected and broken by faults. The Barind Tract is composed of an uplifted and locally tilted series of fault blocks interrupted by a few major river valleys occupying fault troughs (Brammer, 1996).

Floodplain areas include alluvial floodplain and estuarine areas and occupy the remaining 80% of the country. They are composed of predominantly recent alluvial deposits transported from the hills by the rivers. There are numerous natural depressions some of which are abandoned channels formed as a result of change in river courses, and some have been formed in the process of delta building and as a result of tectonic movements of earth.

Five main kinds of landscape can be recognized (Brammer, 2002) in the floodplain areas, which are briefly described below.

(i) Active river floodplain (AEZs 2, 7, 10, 16, 17): These are the youngest alluvial land within and alongside the main rivers which is subject to alternate deposition of new sediments and erosion by shifting channels within the main river course. The temporary alluvial formations (known as chars in Bangladesh) have an irregular relief with stratified sandy and silty deposits.

(ii) Meander floodplains (AEZs 3, 4, 6, 8, 9, 11, 12, 20; parts of 21, 23): These floodplains have been formed by the big meandering rivers. Meander floodplains cover the relatively older parts of the Teesta, Atrai, Brahmaputra-Jamuna, Karatoa-Bangali, Ganges and Surma-Kushiyara river floodplains, away from the present main river channels. They have relatively stable landscapes with complex patterns of curved ridges (former river banks), basins (back swamps) and cut-off channels, crossed by a few active river channels (tributary or distributary channels of the main rivers). Most older floodplain land receives regular additions of new alluvium from the rivers, but some young floodplain land near to active channels (especially on the Jamuna floodplain) receives new deposits during high floods.

(iii) Piedmont plains (AEZs 1, 22; parts of 23): These are characterized by gently sloping land at the foot of the hills composed of colluvial and alluvial sediments (deposited by rivers and streams subject to flash floods) and a drainage pattern of a braided river.

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They include the Old Himalayan Piedmont plain at the foot of the Himalayas and active alluvial fans at the foot of the Northern and Eastern Hills (including parts of the Chittagong Coastal Plain).

Figure 2.9: Location of Agro-Ecological Zones (Source: BARC-GIS Project-2000)

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(iv) Estuarine floodplains (AEZs 18, 19): They are characterized by smooth, almost horizontal levels underlain by silts deposited uniformly both in the lateral and vertical directions under estuarine conditions. These floodplains are divided into the young part (AEZ 18) adjoining the Meghna estuary which is still subject to tidal flooding (where not embanked) and to new accretion and erosion by shifting estuarine channels, and the stable, old part (AEZ 19) which no longer receives new alluvial sediments and is no longer flooded by the tidal water.

(v) Tidal floodplains (AEZs 13; parts of 23): These are characterized by a distinctive, almost-level landscape crossed by innumerable, interconnecting tidal rivers and creeks following a zigzag pattern and flood levels lower than on meander plains. Under natural conditions, the land is subject to flooding with silty water at high tides during at least a part of the year, but many areas have been embanked and thus are cutoff from tidal flooding and sedimentation. On the Ganges tidal Floodplain, tidal water is saline throughout the year in the south-west and fresh throughout the year in the north-east; in between is a zone where floodwater is fresh in the monsoon season and saline for part or all of the dry season.

Table 2.1: Area of Agro-Ecological Zones (Source: FAO, 1988; Brammer, 2002) Area AEZ No. Agro-Ecological Zone

sq.miles Km2 % of

country

1 Old Himalayan Piedmont Plain 1549 4008 2.772 Active Teesta Floodplain 323 836 0.583 Teesta Meander Floodplain 3658 9468 6.544 Karatoa-Bangali Floodplain 994 2572 1.785 Lower Atrai Basin 329 851 0.596 Lower Punarbhaba Floodplain 50 129 0.097 Active Brahmaputra-Jamuna Floodplain 1233 3190 2.208 Young Brahmaputra and Jamuna Floodplains 2289 5924 4.099 Old Brahmaputra Floodplain 2794 7230 4.9910 Active Ganges Floodplain 1288 3334 2.3011 High Ganges River Floodplain 5103 13205 9.1212 Low Ganges River Floodplain 3079 7968 5.5013 Ganges Tidal Floodplain 6594 17066 11.7814 Gopalganj-Khulna Beels 867 2247 1.5515 Ariel Beel 56 144 0.1016 Middle Meghna River Floodplain 600 1555 1.0717 Lower Meghna River Floodplain 351 909 0.6318 Young Meghna Estuarine Floodplain 3581 9269 6.4019 Old Meghna Estuarine Floodplain 2991 7740 5.3420 Eastern Surma-Kushiyara Floodplain 1786 4622 3.1921 Sylhet Basin 1767 4573 3.1622 Northern and Eastern Piedmont Plains 1560 4038 2.7923 Chittagong Coastal Plains 1437 3720 2.5724 St. Martin's Coral Island 3 8 0.01

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25 Level Barind Tract 1591 5049 3.4926 High Barind Tract 618 1600 1.1027 North-eastern Barind Tract 417 1079 0.7428 Madhupur Tract 1640 4244 2.9329 Northern and Eastern Hills 7021 18171 12.5530 Akhaura Terrace 44 113 0.08 Total area 55913 144836 100.00

2.6 Soils

Bangladesh has a wide diversity of soils between and within regions, within villages, between neighboring fields and even within individual field. They often occur in complex patterns. This results in diverse and complex patterns of land use, crop suitability, soil fertility and agronomic practices in many parts of Bangladesh. The diversity and complexity have important implications for land use planning, agricultural research, agricultural extension and the collection of crop statistics. They also mean that the impact of natural disasters can vary considerably between regions, within different regions, and on different land and soil types within a village (Brammer, 2002). In many areas soil resources are being degraded due to improper use of land, fertilizer, irrigation, intensive cropping and some other activities.

Broadly, the soil resource of Bangladesh could be divided into three major groups: floodplain, hill and terrace soils. Figure 2.10 presents the highly generalized soil map of Bangladesh showing the overall distribution of 18 principal soil types of floodplain, hill and terrace soils. The soils of the two terraces covering 8 per cent of the total area are diverse, ranging from deep, reddish brown friable well drained clay loams to grey, poorly drained silty top soils over clay on level highlands. The hilly areas spreading over 12 per cent of the total land surface have mainly loamy soils of shallow depth, not suited for the cultivation of shallow-rooted crops because of the poor water-holding capacity.

Floodplain Soils. The floodplain soils are alluvial deposits ranging from sandy soils deposited on higher ridges, silty clay loams on the lower ridges, and silty clays and clays in the depressions occupying 80 per cent of the country's land area. Fresh alluvium is extensively deposited closer to the rivers, while the older deposits further away from the river are conducive to plant growth. There are 12 general soil types under the floodplain soils. These are: (1a) Calcareous Alluvium (non-saline), (1b) Calcareous Alluvium (seasonally saline), (2) Non-calcareous Alluvium, (3) Calcareous Grey Floodplain Soils, (4) Calcareous Dark Grey Floodplain Soils, (5a) Non-calcareous Grey Floodplain Soils (non-saline), (5b) Non-calcareous Grey Floodplain Soils (seasonally saline), (6) Noncalcareous Brown Floodplain Soils, (7) Non-calcareous Dark Grey Floodplain Soils, (8) Noncalcareous Dark Grey Floodplain Soils and Peat, (9) Black Terai Soils, (10) Acid Basin Clays, (11) Acid Sulphate Soils, and (12) Grey Piedmont Soils. The Gangetic alluvium is rich in calcium, magnesium and potassium, and also contains free calcium carbonate. The soils are characterized by nitrogen and phosphate deficiency and locally by strong alkalinity. The pH range is 7.0 to 8.5. The Teesta silt tract soils are sandy to sandy loam in texture, without any profile development. They are flooded every year and as a result are replenished by fresh deposits every year. The pH varies from 5.5 to 6.8. The coastal floodplain is subject to

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flooding by saline water at high tides. The soil is saline and in general neutral but tends to be on the alkaline side, with pH from 6.9 to 7.5 (Rahman et al., 1990).

The seasonal flooding characteristics have an important influence on physical and biological properties of soil, and therefore have an important bearing on the land use and agricultural potential. The agro-ecological zones are separated on the basis of important differences between them in physiography, soils and flooding characteristics (FAO, 1988).

Terrace Soils. Considering that they have all developed over or from the uniform Madhupur Clay, a surprising diversity of soils occurs on the Madhupur and Barind Tracts and on the

Figure 2.10: Map of general soil types [Source: BARC/FAO/UNDP GIS Project BGD/95/006]

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related Akhaura Terrace. They range from red to grey, deep to shallow, level to sloping, well drained to poorly drained, and from calcareous to very strongly acid. Most have a low moisture-holding capacity, so they are easily prone to drought, and natural fertility generally is low. The proportions in which the different soils occur vary greatly between the three tracts.

Hilly soils. These include a wide range of soils developed over consolidated and unconsolidated sandstones, siltstones and shales which underlie the Northern and Eastern Hills (and their outliers in neighboring physiographic units). They are mainly excessively to moderately well drained, strong brown or yellow-brown, friable, sandy loams to sandy clay loams occurring on steep slopes. The majority is deep over soft or fragmented rock, but shallow soils over hard rock or ironpan (laterite) occur locally. Almost all hill soils are strongly to extremely acidic, moderately to rapidly permeable, low in moisture holding capacity and low in natural fertility with very limited agricultural potential. They are best suited for tree crops or forest production.

2.7 Inundation land types

Bangladesh has a total area of 14.7 Mha and a net cultivable area of around 8.64 Mha (BADC, 2007). On most floodplain and valley land, cropping patterns are primarily determined by the seasonal flooding regime, i.e. the dates when inundation begins and ends, the depth of inundation at peak levels and the risk of damage to crops by early, high or late floods. The depth of flooding is a key factor in the choice of cropping patterns. For example, in deeply flooded areas rice is broadcast as deepwater Aman. In less flooded areas the rice is transplanted, and farmers can grow HYV aman where the flood risk is low (F0 and some F1). With slightly deeper flooding local T.Aman is preferred to HYV T.Aman, because the latter is shorter strawed and more vulnerable to floods. So the topographic position of land in relation to the monsoon season inundation, i.e. inundation land type, will largely decide the land use type in the country.

Table 2.2 shows the classification of land types depending on the inundation depth. The classification has been standardized from Bangladeshi farmers own classification of land types in relation to normal seasonal flooding (Brammer, 2002). This classification is used in water resources planning. The distribution of inundation land types across the country is shown in Figure 2.11, while the regional distribution as per hydrologic zones and agro-ecological zones are presented in Tables 2.3 and 2.4, respectively.

Table 2.2: Classification of cultivable land by flood depth (Source: Harza, 1984) Land type

Flood depth (cm)

Description of land

Area (Mha)

% Suitability of land to rice cultivation

F0 0-30 High land 4.20 29 HYV rice in wet season F1 30-90 Medium high land 5.04 35 Local varieties of Aus and T. Aman F2 90-180 Medium low land 1.18 12 B. Aman in wet season F3 180-300 Lowland 1.10 8 B. Aman can be grown F4 Over 300 Very lowland 0.19 1 Depth, duration and/ or time of

flooding do not permit growing of B. Aman

Note: Settlements and water bodies cover 15%

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Table 2.3: Regional distribution of inundation land types (Source: Chowdhury et al., 1997; WARPO, 2001b)

% of regional cultivable area Region Net Cultivable Area (NCA) (x 1000 ha) F0 F1 F2 F3 F4

NW 2353 53 33 8 6 0 NC 1056 34 29 18 19 0 NE 1408 29 18 22 30 1 SW 1378 33 43 17 7 0 SC 931 23 58 13 3 3 SE 743 29 36 23 10 2

Figure 2.11: Inundation land types

Land type

HighlandMedium Highland Medium LowlandLow landVery LowlandNo DEM

HighlandMedium Highland Medium LowlandLow landVery LowlandNo DEMSundarbans

HighlandMedium Highland Medium LowlandLow landVery LowlandNo DEM

HighlandMedium Highland Medium LowlandLow landVery LowlandNo DEMSundarbans

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Table 2.4: Inundation land types in agroecological regions (Source: FAO, 1988; Brammer, 2002)

AEZ Region

Highland (%)

Medium Highland (%)

Medium Lowland (%)

Low land(%)

Very Lowland (%)

Settlement + water (%)

1 58 34 1 - - 7 2 2 72 - - - 26 3 35 51 4 1 - 9 4 23 44 14 4 1 14 5 2 8 21 65 - 4 6 - - 10 60 * 30 7 5 37 20 8 - 30 8 18 42 19 9 - 12 9 28 35 20 7 - 10

10 12 33 18 4 - 33 11 43 32 12 2 - 11 12 13 29 31 14 2 11 13 2 78 2 - - 18 14 3 13 41 28 11 4